1. Field of the Invention
This invention relates to a noninvasive continuous blood pressure measuring apparatus for noninvasively, continuously measuring blood pressure and a method of noninvasively measuring continuous blood pressure.
2. Description of the Prior Art
A noninvasive continuous blood pressure measuring apparatus for noninvasively, continuously measuring blood pressure is known. An apparatus and a method for measuring an induced perturbation to determine a blood pressure is disclosed in U.S. Pat. No. 5,590,649. In this prior art apparatus, a monitor for continuously determining a patient""s physiological parameter includes a means for obtaining a periodic calibration measurement of the patient""s physiological parameter. An exciter, positioned over an artery of the patient induces an exciter waveform into the patient""s arterial blood. A noninvasive sensor, positioned over the artery, senses a hemoparameter and provides a noninvasive sensor signal output representative of the hemoparameter. A processor receives the calibration measurement and noninvasive sensor signal output. The processor determines a SC offset based on the calibration measurement and processes the noninvasive sensor signal to continuously determine the patient""s physiological parameter.
The aim of the present invention is to provide a superior noninvasive continuous blood pressure measuring apparatus and a superior method of noninvasively measuring continuous blood pressure.
According to this invention, there is provided a first noninvasive continuous blood pressure measuring apparatus including: an oscillator for generating an oscillation signal having a desired frequency and a desired amplitude; a substrate; a plurality of exciters arranged on the substrate in a direction responsive to the oscillation signal for inducing exciter waveforms in an artery and a blood in the artery of a living body; a plurality of sensors respectively arranged on the substrate in the direction a predetermined interval apart from the exciters for receiving induced exciter waveforms transmitted through the artery from the living body and outputting detection signals; a multiplexer for effecting recurrently switching and time-divisionally outputting outputs of the sensors; a determining and selecting portion responsive to the multiplexer for determining one of the outputs in accordance with a predetermined judging condition and for selecting and outputting one of the outputs; a calibration hemadynamometer for detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; a calculating portion for receiving the absolute values from the hemadynamometer and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and one of the outputs from the determining and selecting portion and the absolute values; and a display for displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted by the calculation portion.
In the first noninvasive continuous blood pressure measuring apparatus, the substrate correspondingly arranges the exciters and the sensors such that each pair of each of the exciters and each of the sensors is arranged in the direction and the exciter and the sensor of each pair are arranged in a second direction perpendicular to the direction, the apparatus further including an attaching unit for attaching the substrate to the living body.
In the first noninvasive continuous blood pressure measuring apparatus, the substrate may correspondingly arranges the exciter and the sensors such that each pair including two of the sensors and one of the exciter arranged between the two of the sensors with the predetermined distance is arranged in the direction, the apparatus may further include an attaching unit for attaching the substrate to the living body.
The first noninvasive continuous blood pressure measuring apparatus may further include: a plurality of a/d converters for respectively a/d-converting the detection signals and supplying converted signals to the determining and selecting portion as the outputs of the sensors.
According to this invention, there is a second noninvasive continuous blood pressure measuring apparatus is provided which includes: an oscillator for generating an oscillation signal having a desired frequency and a desired amplitude; an exciter arranged responsive to the oscillation signal for inducing an exciter waveform in an artery and a blood in the artery of a living body; a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; a calibration hemadynamometer for detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; a calculating portion for receiving absolute values from the calibration hemadynamometer and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal and the absolute values; and a display for displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted by the calculation portion.
In the second noninvasive continuous blood pressure measuring apparatus, the oscillator may include: a clock signal generation circuit for generating a clock signal; a processor responsive to frequency control data and the clock signal for successively generating frequency signal data indicative of amplitude in time base in accordance with the frequency control data; a d/a converter for converting the frequency signal data; and a filter for low-pass filtering an output of the d/a converter and outputting the oscillation signal of which frequency is controlled in accordance with the frequency data.
In the second noninvasive continuous blood pressure measuring apparatus, the oscillator may include: a clock signal generation circuit for generating a clock signal; a numerically-controlled oscillator responsive to frequency control data and the clock signal for successively generating frequency signal data indicative of amplitude in time base in accordance with the frequency control data; a d/a converter for converting the frequency signal data; and a filter for low-pass filtering an output of the d/a converter and outputting the oscillation signal of which frequency is controlled in accordance with the frequency data.
In the second noninvasive continuous blood pressure measuring apparatus, the oscillator may include: a clock signal generation circuit for generating a clock signal; a processor responsive to frequency control data for generating at least one cycle of frequency signal data and storing one cycle of frequency signal data in a look-up table; an address signal generating circuit for generating an address signal in response to the clock signal to operate the look-up table to successively read and output one cycle of frequency data indicative of an amplitude of the oscillation signal; a d/a converter for converting one cycle of frequency data; and a filter for low-pass filtering an output of the a/d converter and outputting the oscillation signal of which frequency is controlled in accordance with the frequency data.
In the second noninvasive continuous blood pressure measuring apparatus, the oscillator may include: a PLL circuit responsive to frequency control data for successively generating a frequency signal; and a filter for low-pass filtering the frequency signal and outputting the filtered frequency signal as the oscillation signal of which frequency is controlled in accordance with the frequency data.
According to this invention, there is provided a third noninvasive continuous blood pressure measuring apparatus which includes: an oscillator for generating an oscillation signal having a desired frequency and a desired amplitude; an exciter responsive to the oscillation signal for inducing an exciter waveform in an artery and a blood in the artery of a living body; a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; an a/d converter for a/d-converting the detection signal; a calibration hemadynamometer for detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; a microprocessor including a filter portion and a calculating portion, the filter portion band-pass-filtering the detection signal from the a/d converter, the calculating portion receiving the absolute values from the calibration hemadynamometer and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal from the filter portion and the absolute values; and a display for displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted by the calculation portion.
According to this invention, there is provided a fourth noninvasive continuous blood pressure measuring apparatus which includes: an oscillator for generating an oscillation signal having a desired frequency and a desired amplitude; an exciter responsive to the oscillation signal for inducing an exciter waveform in an artery and a blood in the artery of a living body; a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; a calibration hemadynamometer for detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; a bandpass filter for band-pass-filtering the detection signal from the sensor; an a/d converter for a/d-converting the detection signal from the bandpass filter; a microprocessor including a calculating portion for receiving the absolute values from the calibration hemadynamometer and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal from the a/d converter and the absolute values; and a display for displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted by the calculation portion.
According to this invention, there is provided a fifth noninvasive continuous blood pressure measuring apparatus which includes: an oscillator for generating an oscillation signal of which frequency is controlled; an exciter responsive to the oscillation signal for inducing an exciter waveform in an artery and a blood in the artery of a living body; a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; a calibration hemadynamometer for detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; a frequency determining portion responsive to the sensor for controlling the oscillator to successively control the frequency at different frequencies and determining one of the difference frequencies in accordance with the detection signal outputted at different frequencies, and then, controlling the oscillator to continuously generate the oscillation signal at one of the different frequencies; a calculating portion responsive to the frequency determining portion for receiving absolute values from the calibration hemadynamometer and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal at one of the different frequencies and the absolute values; and a display for displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted by the calculation portion.
In the fifth noninvasive continuous blood pressure measuring apparatus, the frequency determining portion may detect attenuations in the detection signal at different frequencies and determine one of the difference frequencies in accordance with a minimum of the attenuations.
In the fifth noninvasive continuous blood pressure measuring apparatus, the frequency determining portion may detect dispersions in amplitudes of the detection signal at different frequencies and determine one of the different frequencies in accordance with a minimum of the dispersions.
In the fifth noninvasive continuous blood pressure measuring apparatus, the frequency determining portion may detect phase shifts in the detection signal at different frequencies and determine one of the difference frequencies in accordance with a maximum of the phase shifts.
In the fifth noninvasive continuous blood pressure measuring apparatus, the frequency determining portion may detect attenuations in the detection signal at different frequencies, detect dispersions in amplitudes of the detection signal at the different frequencies, and detect phase shifts in the detection signal at the different frequencies, obtain estimation values at the different frequencies through an estimating function for estimating the attenuations, the dispersions, and the phase shifts, and determine one of the difference frequencies in accordance with the estimation values at the different frequencies.
According to this invention, there is provided a sixth noninvasive continuous blood pressure measuring apparatus which includes: an oscillator for generating an oscillation signal of which waveform is controlled; an exciter responsive to the oscillation signal for inducing an exciter waveform in an artery and a blood in the artery of a living body; a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; a calibration hemadynamometer for detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; a waveform determining portion responsive to the sensor for controlling the oscillator to control the oscillation signal successively have different waveforms and determining one of the difference waveforms in accordance with the detection signal outputted at different waveforms and then, controlling the oscillator to continuously generate the oscillation signal at one of the different waveforms; a calculating portion responsive to the frequency determining portion for receiving absolute values from the calibration hemadynamometer and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal at one of the different waveforms and the absolute values; and a displaying for displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted by the calculation portion.
In the sixth noninvasive continuous blood pressure measuring apparatus, the waveform determining portion may detect attenuations in the detection signal at the different waveforms and determine one of the difference waveforms in accordance with a minimum of the attenuations.
In the sixth noninvasive continuous blood pressure measuring apparatus, the waveform determining portion may detect dispersions in amplitudes of the detection signal at the different waveforms and determines one of the difference waveforms in accordance with a minimum of the dispersions.
In the sixth noninvasive continuous blood pressure measuring apparatus, the waveform determining portion may detect phase shifts in the detection signal at the different waveforms and determine one of the difference waveforms in accordance with a maximum of the phase shifts.
In the sixth noninvasive continuous blood pressure measuring apparatus, the waveform determining portion may detect attenuations in the detection signal at the different waveforms, detect dispersions in amplitudes of the detection signal at the different waveforms, and detect phase shifts in the detection signal at the different waveforms, obtain estimation values at the different waveforms through an estimating function for estimating the attenuations, the dispersions, and the phase shifts, and determine one of the difference waveforms in accordance with the estimation values at the different waveforms.
According to this invention, there is provided a first method of noninvasively measuring continuous blood pressure including the steps of: generating an oscillation signal of which frequency is controlled; providing an exciter responsive to the oscillation signal inducing an exciter waveform in an artery and a blood in the artery of a living body; providing a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; controlling the oscillation signal to successively control the frequency at different frequencies and determining one of the difference frequencies in accordance with the detection signal outputted at different frequencies; continuously generating the oscillation signal at one of the different frequencies; receiving absolute values and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal at one of the different frequencies and the absolute values; and displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted.
According to this invention, there is provided a second method of noninvasively measuring continuous blood pressure including the steps of: generating an oscillation signal of which waveform is controlled; providing an exciter responsive to the oscillation signal inducing an exciter waveform in an artery and a blood in the artery of a living body; providing a sensor arranged a predetermined interval apart from the exciter for receiving the induced exciter waveform transmitted through the artery from the living body and outputting detection signal; detecting absolute values of a maximum blood pressure and a minimum blood pressure of the living body; controlling the oscillation signal to successively control the frequency at different waveforms and determining one of the difference waveforms in accordance with the detection signal outputted at different waveforms; continuously generating the oscillation signal at one of the different waveforms; receiving absolute values and successively calculating and outputting an instantaneous blood pressure value from a phase relation between the oscillation signal and the detection signal at one of the different waveforms and the absolute values; and displaying a continuous blood pressure variation from the instantaneous blood pressure successively outputted.